Bacterial leaf streak disease of Rice: A silent constraint to Rice production in Uganda

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Bacterial leaf streak disease (BLS) caused by Xanthomonas oryzae pv oryzicola is one
of the emergent biotic constraints to rice production in Africa. The disease, which can
cause yield loss of up to 60% on susceptible cultivars, was observed in Uganda in the rice
growing districts of Namutumba, Butaleja and Iganga in 2014. As such there is limited data
on the distribution of bacterial leaf streak disease in rice growing areas of Uganda. Using a
systematic sampling survey, 176 rice fields at tillering to panicle initiation stages in 14 rice
growing districts of Uganda were assessed for the prevalence of BLS disease. Results show
a high prevalence of bacterial leaf streak disease, where 71.4% of the districts surveyed
had the disease. Data collected also revealed significant differences (P < 0.001) in BLS
incidence and severities between the districts surveyed. The results further indicated that
rice fields where improved varieties and clean seeds were planted had very low incidences
and severity. The high prevalence of BLS disease in the rice growing districts may be due
to existence of highly virulent BLS pathogens, favourable environment (high humidity and
warm temperature) and cultivation of susceptible local rice genotypes. Poor rice residue
management, poor field hygiene and utilization of home saved rice seeds by majority of the
farmers could also account for the wide occurrence of BLS disease since these lead to the
build-up of primary inoculum. For sustainable management of this disease, there is need
to create awareness on the wide occurrence of BLS disease in Uganda, educate farmers
on management of the disease, understand the population structure of BLS pathogen in
Uganda and identify genetically stable sources of resistance to the pathogen under Uganda’s
conditions.